Updark’s smile was harsh. ‘And not merely by the mad Mullahs. His fear of Israel, too, would be justified. Even before the treaty was signed, there were a number of reasons why you wouldn’t want to be a scientist in Iran, among the most persuasive being that the Israelis bump you off.’

Hissop consulted his clipboard again. ‘When the Israeli general in charge was asked how far he would go to stop the Iranian nuclear programme, he replied: “Two thousand kilometres.” Even so, if Mossad is buzzing around Marvar’s lab, then, as Lionel said, it’s likely so too are the Russians, Saudis and Chinese.’

‘And I tell you this,’ said Updark testily, ‘they’re not all descending on our dreaming spires because they sniff the sweet scent of cheap energy. The popular idea peddled by Professor Whitton et alii that fusion can have no military implication is balderdash. This, in case you’re still curious, is why we have brought you here today. This is why we have invested so much energy in questioning you and requesting your help. The ramifications, John, are extremely serious. And I do mean extremely. If Marvar has found a simple way to make a fusion explosion, it would make a lot of important people around the world very depressed. You then have the possibility of giving all other “bad guys” – I’m sounding like the American president – the chance to control the most lethal weapon ever invented, and to do it clandestinely, at little cost. I’m sure you recall that incident on the tube train in Parsons Green. One delinquent teenager with a grudge and a shopping bag of nails was enough to paralyse the nation for two days. Imagine what a dedicated group of disaffected teenagers each with a carrier bag containing a fusion device could do. If you’re prepared to blow yourself up to kill one person, why stop there? Why not kill half a million? Coming to a theatre of death near you … No. We’ve been to that movie, don’t like how it ended.’

Dyer said nothing. He drank his coffee. The mug was institutional white, like his landlord’s mugs in Jericho. He thought of Marvar holding his by the window, not drinking. Could he have taken Samir to the Lake District, in the footsteps of Wordsworth and Coleridge, to mull over in peace what to do? Is that why he had asked Dyer not to speak of his plans?

Finally, Dyer said, partly to deflect Updark: ‘What if no one has kidnapped him? What if he’s gone to ground for some other reason?’

‘Such as?’

Dyer shrugged. ‘Say to put his ducks in order before making a public announcement? There’d be a Nobel in this, wouldn’t there?’

‘And how!’ said Hissop. ‘Although, if it was developed at the Clarendon, Whitton would want to take his portion of credit.’